Electrical connection with reduced topography

ABSTRACT

The formation of substrate electrical connections on thin film heads is one source of resulting surface topography. In accordance with one implementation, such topography can be reduced by a process that includes depositing a first layer of basecoat, creating electrical recessed vias in one or more plating processes, and depositing a second layer of basecoat on top of the electrical vias and on top of the first layer of basecoat. In one implementation, the first and second layers of basecoat have a combined height that is substantially equal to the height of the electrical recessed vias. In one implementation, the resulting topographical features are small enough that they can be planarized without creating a lack of uniformity in the total basecoat thickness across the wafer.

SUMMARY

Implementations described and claimed herein provide for a layeredmicroelectronic structure comprising a basecoat layer on a substrate; anelectrical via in the basecoat layer that contacts the substrate and hasa base portion and an upper portion, the upper portion having an outercasing and an interior prong; and a contact pad that contacts the upperportion and is axially aligned with the base portion and the upperportion.

This Summary is provided to introduce an election of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Otherfeatures, details, utilities, and advantages of the claimed subjectmatter will be apparent from the following more particular writtenDetailed Description of various implementations and implementations asfurther illustrated in the accompanying drawings and defined in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example air-bearing surface of a transducer headmanufactured using NIL and/or optical lithography techniques.

FIG. 2 illustrates a first example photoresist exposure and developmentstep in creating substrate electrical connections in a transducer head.

FIG. 3 illustrates an example substrate-etching step in creatingsubstrate electrical connections in a transducer head according.

FIG. 4 illustrates a photoresist deposition step in creating substrateelectrical connections in a transducer head according to anotherimplementation.

FIG. 5 illustrates another example photoresist exposure and developmentstep in creating substrate electrical connections in a transducer head.

FIG. 6 illustrates an example electroplating step in creating substrateelectrical connections in a transducer head.

FIG. 7 illustrates an example result of a feature-building step increating substrate electrical connections in a transducer head.

FIG. 8 illustrates yet another example photoresist exposure anddevelopment step in creating substrate electrical connections in atransducer head.

FIG. 9 illustrates yet another example electroplating step in creatingsubstrate electrical connections in a transducer head according.

FIG. 10 illustrates an example additional basecoat layer applicationstep in creating substrate electrical connections in a transducer head.

FIG. 11 illustrates an example contact pad connection step in creatingsubstrate electrical connections in a transducer head.

FIG. 12 illustrates a flow-chart of example operations for creatingsubstrate electrical connections of a transducer head that result in areduced wafer topography.

DETAILED DESCRIPTION

Improvements in magnetic storage media technology allow for the arealrecording densities on magnetic discs that are available today. However,as areal recording densities increase, smaller and more sensitive thinfilm heads are desired. Fabrication of thin film heads for densitiesabove 1 Tbpsi require the formation of complex feature geometries thatmay not readily and cost-effectively be created using traditionaloptical lithography techniques or by alternatives such as ebeamlithography. These complete feature geometries can, however, be createdusing NanoImprint Lithography (NIL) techniques.

NanoImprint lithography (NIL) offers advanced pattern fidelity similarto ebeam lithography, but is significantly faster and offers throughputsimilar to optical lithography. Unlike optical lithography patterning,NIL patterning relies on direct contact between a wafer and a templatethat is pressed against the wafer. This direct contact permits capillaryforces to draw droplets of liquid photoresist on the wafer intopatterned grooves on the template. However, when significant topographyis present on the wafer prior to NIL imprinting, such capillary forcesmay be insufficient to draw the liquid photoresist into the cavities. Insuch cases, NIL imprinting can be problematic.

As used herein, the term “significant surface topography” refers totopographical features created on the surface of a wafer that are largeto be problematic in a NIL imprinting process. For example, significantsurface topography may refer to features large enough to prevent a NILtemplate from making direct and substantially uniform contact with aphotoresist on the wafer during NIL patterning. Typically, such contactis prevented when two or more microns of topography are present on thesurface of the wafer. However, such contact may be prevented in otherimplementations when there is substantially between 0.5 and 1.0 μm oftopography on the wafer. Alternatively, significant surface topographymay refer to features less than 0.5 microns that create other problemsin NIL patterning.

One source of significant surface topography in thin film head creationis the addition of substrate electrical connections to the thin filmheads. Although polishing processes can remove some surface topography,polishing is time consuming and can create wafer uniformity problemswhen 2.5 microns of topography or greater are present on the wafer.Additionally, polishing is not always time or cost efficient.Implementations of the methods disclosed herein significantly reducesurface topography formed incident to the creation of substrateelectrical connections on a transducer head.

FIG. 1 illustrates an example air-bearing surface of a transducer head100 manufactured using NIL and/or optical lithography techniques. Thetransducer head 100 is a laminated structure with a variety of layersperforming a variety of functions. A substrate 103 serves as a mountingsurface for the transducer head 100 components and connects thetransducer head 100 to an air-bearing slider (not shown). The substrate103 is preferably a hard material with high thermal stability, such asaluminum-titanium carbide (AlTiC). In one implementation, the substrate103 is a layer of AlTiC that is approximately 1210 μm thick.

A nonmagnetic, nonconductive basecoat 104 is deposited on the substrate103. The basecoat 104 may be, for example, aluminum oxide (Al₂O₃),silicon oxynitride (Si_(x)O_(y)N_(z)), aluminum nitride, siliconnitride, or silicon oxide. In one implementation, the basecoat layer 104has a height (y-direction) that is substantially between three and tenmicrons thick.

A read element 102 is sandwiched between a lower shield 106 and an uppershield 108. The shields 106 and 108 isolate the read element 102 fromelectromagnetic interference, primarily y-direction interference, andserve as electrically conductive first and second electrical leadsconnected to processing electronics (not shown). Further, side shields110 isolate the read element 102 from electromagnetic interference,primarily x-direction interference and/or z-direction interference.Nonmagnetic, nonconductive isolation layers 112 electrically isolate thelower shield 106 and the read element 102 from soft magnetic ornonmagnetic side shields 110. The read element 102 is configured to readdata from a magnetic media rotating below an air-bearing surface(represented by the x-y plane) of the transducer head 100. In at leastone implementation, the read element 102 is created through a NILimprinting process.

The transducer head 100 also includes a barrier layer 114 between a coil116 and the shield 108. The coil 116 in combination with a write pole118 receives a write signal from the processing electronics and changesthe magnetic polarization of magnetic regions on an adjacent magneticmedia (not shown), thereby writing the data from the write signal to themagnetic media.

To avoid the build-up of electro-static charge and certain electricalshock events, metal features 124 (which may also be referred to hereinas “substrate electrical connections” or “electrical vias”) are embeddedin the basecoat 104 to connect one or more contact pads (not shown) onthe lower shield 106 to the substrate 103. Forming such electricalconnections 124 via one or more of the implementations disclosed hereinmay result in surface topography that is reduced as compared to existingmethods.

The transducer head 100 is attached to an air-bearing slider (not shown)at a distal end of an actuator arm flexure (not shown). The sliderenables the transducer head 100 to fly in close proximity above acorresponding surface of the adjacent magnetic media. The air-bearingsurface of the transducer head 100 faces the magnetic media. Theactuator arm flexure attached to a cantilevered actuator arm (not shown)and the actuator arm flexure is adjustable to follow one or more tracksof magnetic data on a magnetic media (not shown). Electrical wires (notshown) extend along the actuator arm flexure and attach to contact pads(not shown) on the slider that ultimately connect to the transducer head100. Read/write and other electrical signals pass to and from processingelectronics (not shown) to the transducer head 100 via the electricalwires and contact pads.

Typically, multiple transducer heads that are the same or similar to thetransducer head 100 are formed on a semi-conductor wafer at a factoryand then separated by a dicing process. Therefore, multiple transducerheads may be formed simultaneously via the processes disclosed herein.One or multiple substrate electrical connections may be included in asingle transducer head.

The steps discussed below with respect to FIGS. 2-11 describeimplementations of one or more methods for building substrate electricalconnections in thin film transducer heads. Each of FIGS. 2-11 shows across-section of a transducer head taken across the x-y plane of FIG. 1.

FIG. 2 illustrates a first example photoresist exposure and developmentstep in creating substrate electrical connections in a transducer head200. A patterned photoresist 210 having recesses 220 and 222 formedtherein is shown on top of a first basecoat layer 204. The firstbasecoat layer 204 is above and in contact with a substrate 203, whichserves as a mounting surface for the transducer head 200.

The first basecoat layer 204 is a nonmagnetic, nonconductive materialsuch as Al₂O₃ that is deposited on the substrate 203. The first basecoatlayer 204 has a height (y-direction) that is less than a desired finalbasecoat height for the transducer head 200. In one implementation, theheight of the first basecoat layer 204 deposited on the substrate 203 isbetween forty and eighty percent of a final basecoat thickness that isto be deposited on the transducer head. In another implementation, theheight of the first basecoat layer 204 deposited on the substrate 203 isbetween forty and eighty percent of a final basecoat thickness prior toa planarization process.

The substrate 203 is a hard, thermally stable material such as AlTiC,which may be of considerably greater height than the first basecoatlayer 204. In one implementation, the substrate layer has a height ofapproximately 1210 μm, and the first basecoat layer 204 has a heightthat is approximately three microns.

The patterned photoresist 210 may be either a negative or positivephotoresist and has two recesses (e.g., the recesses 220 and 222) formedtherein. In one implementation, the y-direction height of the patternedphotoresist 210 is between approximately two and eight microns.

To create the patterned photoresist 210, a liquid photoresist layer isdeposited substantially evenly across the transducer head 200. Aphotomask (not shown) having a pattern corresponding to the recesses220, 222 in the patterned photoresist 210 is positioned to mask portionsof the liquid photoresist layer while the unmasked portions are exposedto a high intensity light. This exposure process changes the solubilityof either exposed or unexposed portions of the photoresist layer,depending upon the type of photoresist utilized. After the exposure,portions of the photoresist are removed, such as by a developersolution. In one implementation, the developer solution is an organichighly basic solution.

FIG. 3 illustrates an example substrate-etching step in creatingsubstrate electrical connections in a transducer head 300. During thesubstrate-etching step, holes (e.g., a hole 324) are etched into abasecoat 304 to expose portions of a substrate 303. The etching step maybe either a wet or dry etch and may be performed while a patternedphotoresist (such as the patterned photoresist 210 in FIG. 2) is inplace on the basecoat 304, protecting portions of the transducer headthat will not be etched.

After the etching, the patterned photoresist may be removed. In oneimplementation, the patterned photoresist is removed by a resist-stripthat chemically alters the patterned photoresist so that it no longeradheres to the substrate. Alternatively, the photoresist may be removedby an ashing process.

FIG. 4 illustrates an example photoresist deposition step in creatingsubstrate electrical connections in a transducer head 400. Thetransducer head 400 has a basecoat 404 with holes (e.g., a hole 424)etched therein to expose an underlying substrate 403. A layer of aliquid photoresist 430 is deposited substantially evenly across thetransducer head 400 to coat the basecoat 404 and fill the etched holes,as shown in FIG. 4.

FIG. 5 illustrates another photoresist exposure and development step increating substrate electrical connections in a transducer head 500. Thetransducer head 500 has a basecoat 504 with a number of etched holes(e.g., an etched hole 524) therein, exposing an underlying substrate503. A patterned photoresist 530 is on top of and in contact with thebasecoat 504.

The patterned photoresist 530 is created by depositing a liquidphotoresist layer evenly across the transducer head 500. A photomask(not shown) having a pattern corresponding to the recesses 526, 528 inthe patterned photoresist 530 is positioned to mask portions of theliquid photoresist layer. The masked photoresist layer is then exposedto a high intensity light to change the solubility of portions of thephotoresist. The exposed portions of the photoresist are developed in anaqueous solution, leaving behind the patterned photoresist 530 with tworecesses (e.g., the 526 and 528) therein.

The recesses 526 and 528 in the patterned photoresist 530 are eachvertically aligned with an etched hole (e.g., holes 524 and 532,respectively) in the basecoat 504, such that each of the recesses 526and 528 in the photoresist layer shares a common base with one of theetched holes 524 and 532 in the basecoat 504. However, each of therecesses 526, 528 in the photoresist layer is wider than the width ofthe corresponding etched hole 524 and 532, respectively, in the basecoat504. Therefore, metal may be plated into each of the etched holes 524and 532 and expanded beyond the width of the respective etched holes 524and 532. Plating metal in this manner prevents voids from formingbetween the basecoat 504 and the metal (not shown) during the platingprocess.

FIG. 6 illustrates an example electroplating step in creating substrateelectrical connections in a transducer head 600. Prior to theelectroplating step, a patterned photoresist (such as the patternedresist 530 illustrated atop the basecoat 504 in FIG. 5) is formed on topof a basecoat 604 to protect portions of the transducer head 600 whilemetal (e.g., a metal connection 640) is plated into a number of etchedholes in the basecoat 604 during the electroplating step.

In one implementation, a seed layer (not shown) is deposited on thetransducer head 600 prior to the electroplating step to help the metaladhere to a substrate 603 and a basecoat 604. In one implementation,this seed layer is approximately 0.2 μm thick.

After the metal is plated into the etched holes in the basecoat 604, thepatterned photoresist is removed, leaving behind metal connections(e.g., a metal connection 640) that are in contact with the substrate603 and partially or fully embedded in the basecoat 604. As viewed inthe x-y cross-section of FIG. 6, each of the metal connections has abase portion (e.g., a base portion 636) and two protruding shoulders(e.g., shoulders 638 and 639) on either side of the base portion. Thisstructure, including the base portion and the shoulders is referred tohereinafter as an “electrical recessed via.”

In at least one implementation, the shoulders 638 and 639 of theelectrical recessed via are connected along the x-z plane. For instance,the shoulders 638 and 639 of the electrical recessed via 640 may beopposing sides of a cylindrical shell (i.e., a casing) that arcs intothe x-z plane and extends longitudinally in the y-direction.Alternatively, the shoulders 638 and 639 may be opposing sides of arectangular shell.

In the same or an alternate implementation, the base portion 636illustrated in FIG. 6 a cylindrical, rectangular, or any non-traditionalshape that extends longitudinally in the y-direction and is circular,rectangular, etc. when viewed head-on in the x-z plane.

The metal used to form the electrical recessed vias is an electricallyconductive metal, which may be a variety of materials including, withoutlimitation, Cu and NiFe. The height of the base portion (e.g. the baseportion 636) of each of the electrical recessed vias is substantiallyequal in height (y-direction) to the height of the basecoat 604. Theshoulders of each of the electrical recessed vias (e.g., the shoulders638 and 639) are also substantially equal in height to the height of thebasecoat 604.

FIG. 7 illustrates an example feature-building step in creatingsubstrate electrical connections in a transducer head 700. During thefeature building step, additional features, such as heaters (e.g., aheater 744), bleed resistors (not shown), or other electrostaticdischarge devices are added to a basecoat 704 of the transducer head700.

In one implementation, a patterned photoresist (not shown) is formed onthe transducer head 700 prior to the addition of such features. Thepatterned photoresist may be formed according to the same or similarprocesses as those discussed above with respect to FIGS. 2 and 5. Afterthe additional features are added, the patterned photoresist is removed.

The additional features may be added through any number of processesincluding deposition and electroplating.

FIG. 8 illustrates another example photoresist exposure and developmentstep in creating substrate electrical connections in a transducer head800. An x-y cross section of the transducer head 800 is shown. The crosssection includes a substrate layer 803, a basecoat 804, and a number ofelectrical recessed vias (e.g., an electrical recessed via 840 having abase 836 and shoulders 838 and 839) formed therein. A patternedphotoresist 842 is formed on the transducer head, and is sized andconfigured to allow for plating of additional metal within the recess(e.g., between the shoulders 838 and 839) of each of the electricalrecessed vias.

In one implementation, the patterned photoresist 842 is created by aprocess the same or similar to those processes described with respect tothe patterned photoresists in FIGS. 2 and 5.

FIG. 9 illustrates a second example electroplating step in creatingsubstrate electrical connections in a transducer head 900. During thesecond electroplating step, an interior metal prong (e.g., the interiormetal prong 950) is plated on top of a base (e.g., a base 936) within anupper casing 952 of each of a number of electrical recessed vias formedon the transducer head 900. In one implementation, the interior metalprong is plated in the center of the upper casing. In the same or analternate implementation, the upper casing 952 is a hollow cylindricalshell that arcs into the x-z place and extends longitudinally away fromthe substrate 903 (y-direction). An x-y cross section of the uppercasing 952 (as illustrated in FIG. 9) includes two outer prongs orshoulders 938 and 939 on top of and on opposite sides of the baseportion 936. The interior prong 950 is plated on top of the base andwithin the upper casing (i.e., between the shoulders 938 and 939).

The metal used to form the interior metal prongs of the electrical viasis electrically conductive and may be of the same or a differentmaterial from that utilized to form the base and the upper casing ofeach of the electrical vias. A patterned photoresist (such as thepatterned photoresist 842 illustrated in FIG. 8) may be in place duringthe electroplating, and removed after such plating is complete.

The interior prong 950 has an x-direction cross-section that is lessthan an inner x-direction cross-section or diameter of the upper casing952 (i.e., the spacing between the shoulders 938 and 939) so that theinterior prong 950 does not contact an inner surface of the upper casing952. In one implementation, the y-direction height of the interior prong950 is less than or substantially equal to the height of the uppercasing 952. In another implementation, the height of the interior prong950 is greater than the upper casing 952.

FIG. 10 illustrates an example additional basecoat layer applicationstep in creating substrate electrical connections in a transducer head1000. A cross section of the transducer head 1000, taken across the x-yplane, has a first layer of basecoat 1004 and a number of electricalvias (e.g., electrical vias 1040 and 1044) therein that are in contactwith a substrate 1003 below the first basecoat layer 1004. Each of theelectrical vias has a lower, base portion (e.g., base portion 1036) andan upper, three-pronged portion (e.g., a three pronged portion 1052) incontact with the base portion and extending away from the base portion.

In the additional basecoat layer application step, a second layer ofbasecoat 1046 is deposited in a substantially even manner across thetransducer head 1000, creating a number of “humped” topographicalfeatures (e.g., the topographical features 1048) on the surface of thetransducer head 1000. In one implementation, the combined height of thefirst 1004 and second 1046 layers of basecoat is substantially equal toa total height of the electrical vias. For example, the combined height(y-direction) of the first 1004 and second 1046 layers of basecoat maybe substantially equal to the distance between the bottom of baseportion 1036 to the top of the tallest prong 1038 of the electricalvias.

The topographical features created on the transducer head 1000 incidentto the addition of the second layer 1046 of basecoat may extend awayfrom the substrate 1003 in the y-direction beyond each of the electricalvias by a height that is substantially equal to the second layer 1046 ofbasecoat. In other implementations, the second layer of basecoat 1046may have a height that is shorter or greater than any or all the prongsof the electrical vias.

The first 1004 and second 1046 layers of the basecoat are depositedseparately, with one or more metal plating processes performed inbetween to form the electrical vias. In one implementation, the layer ofbasecoat 1004 has a thickness that is 40 to 80 percent of the combinedthickness of both the first 1004 and second 1046 layers of basecoateither before or after planarization of the transducer head. As aresult, the topographical features created incident to the depositionand plating processes are reduced in height as compared to the height oftopographical features that may result when the basecoat is applied in asingle step. Specifically, such topographical features may be reduced by40 to 80%.

Moreover, the topographical features (e.g., the topographical features1048) are small enough that the transducer head 1000 can be planarized,such as along the dotted line 1050, without creating a significantvariability in a total basecoat height (e.g., the y-direction height ofthe combined first 1004 and second 1046 layers of basecoat). Theplanarization may be performed, for example, by a milling or lappingprocess.

After the planarization of the transducer head 1000, each of theelectrical vias 1040 and 1044 may be exposed to allow for contact withone or more contact pads on a lower shield (not shown) of the transducerhead 1000.

FIG. 11 illustrates an example contact pad connection step in creatingsubstrate electrical connections in a transducer head 1100. A crosssection of the transducer head 1100, taken across the x-y plane, has afirst layer of basecoat 1104, a second layer of basecoat 1146, and anumber of electrical vias (e.g., electrical vias 1140 and 1144) thereinthat are in contact with a substrate 1103 below the first basecoat layer1104. Each of the electrical vias has a base portion (e.g., base portion1136) and an upper portion (e.g., an upper portion 1152).

The upper portion 1152 includes an outer casing or shell (illustrated byouter prongs 1172 and 1174 in the cross-sectional view of FIG. 6) thatmay be a cylindrical, rectangular, or non-traditional shape. In oneimplementation, the upper portion 1152 is a cylindrical shell that arcsinto the x-z place and extends longitudinally away from the substrate1103 (y-direction). The upper portion 1152 also includes an interiorprong (e.g., an interior prong 1170) within the outer casing. Both theouter casing (illustrated by opposing sides 1172 and 1174 of the outercasing) and the interior prong 1170 are in contact with the base portion1176. The interior prong 1170 may be round, oval, rectangular, or anyother non-traditional shape when viewed head-on in the x-z plane. In thesame or an alternate implementation, the base portion 1136 of theelectrical via is circular, rectangular, or any non-traditional shapewhen viewed head-on in the x-z plane.

The upper portion 1152 is axially aligned with the base portion 1136along an axis 1164. As used herein, the term “axially aligned” refers toan alignment perpendicular to the substrate layer 1103 (e.g., ay-direction alignment) along an axis 1164 between two or more structuresthat each physically intersect the axis 1164. In one implementation, theaxis 1164 intersects a center of the base portion 1136.

A contact pad (e.g., a contact pad 1160) is arranged on top of each ofthe electrical vias such that it is axially aligned with the upperportion (e.g., an upper portion 1152) and the base portion (e.g., thebase portion 1136) along the axis 1164 of the electrical via. In oneimplementation, the contact pad 1160 and the interior prong 1170 areaxially aligned with a center of the base portion 1136.

In the implementation illustrated by FIG. 11, the upper portion 1152 ofthe electrical via 1140 has a width (e.g., an x-direction edge-to-edgecross section 1166) that is greater than a width (e.g., an x-directionedge-to-edge cross section 1168) of the base portion 1136.

The contact pad 1160 is in contact with both the interior prong 1170 andthe outer casing (illustrated by opposing sides 1172 and 1174 of theouter casing) of the upper portion of the electrical via 1140. In oneimplementation, electricity may readily flow through each of the contactpads 1160, 1162 through the corresponding electrical vias 1140 and 1144.

In one implementation, the contact pad 1162 is formed by depositing aseed layer (not shown) on the transducer head 1100 to help the contactpad 1162 adhere to the transducer head 1100. A patterned photoresist(not shown) is created on the transducer head 1100 with a recesspatterned therein to receive the contact pad 1162. Metal material isthen electroplated into the recess to form the contact pad 1162 and thepatterned resist is removed. The surface of the transducer head 1100 maythereafter be dry-etched to remove the seed layer and a top portion ofthe contact pad.

FIG. 12 illustrates a flow-chart of example operations for creatingsubstrate electrical connections of a transducer head that result in areduced surface topography. A basecoat etching operation 1205 etchesholes in a first layer of a basecoat on a substrate. The first layerbasecoat may be a nonmagnetic, non-conductive material such as Al₂O₃,and the substrate wafer is preferably a hard, thermally stable materialsuch as AlTiC. In one implementation, the first layer of the basecoathas a thickness that is 40 to 80 percent of a desired final basecoatthickness. In the same or a different implementation, the final desiredbasecoat thickness is between 3 and 7 microns.

Several precursor steps may be employed to etch the holes in the firstlayer of the basecoat. First, recesses are patterned into a photoresistlayer deposited on the substrate. A layer of liquid photoresist, whichmay be a negative or positive photoresist, is deposited across the topof the basecoat and a patterned photomask is positioned to mask thephotoresist. While masked, the layer of liquid photoresist is exposed toa high intensity light to change the solubility of either the exposed orthe unexposed portions of the liquid photoresist, depending on the typeof photoresist utilized. The modified portions of the resist arethereafter removed by a developer solution, which may be, for example,an organic highly basic solution. In an implementation where a positiveresist is used, the exposed portions of the resist have their solubilitymodified during the exposure. Here, the developer solution is applied todissolve the exposed portions of the resist so that the unexposedportions remain on the wafer.

After the photoresist is patterned, holes are etched into the basecoatvia an etching process, which may be either wet or dry. Thereafter, thepatterned photoresist is stripped away from the basecoat, such as byusing a resist strip.

The etched holes each have a depth substantially equal to the depth ofthe basecoat so that the underlying substrate is exposed at the base ofeach of the etched holes. The width of the etched holes may vary, but inone implementation, the width is substantially between 2 and 50 microns.

A building operation 1210 plates metal into each of the etched holes inthe basecoat. The building operation 1210 includes several precursorsteps. First, a thin seed layer is deposited across the of thetransducer head. The seed layer may be any one of a number of metalshaving properties to help the metal adhere to the substrate andbasecoat. For example, the seed layer may be Cu, NiFe, CoFe, CoNiFe,CoPt, Cr, Ru, Ta, Pt, or Au. In one implementation, the seed layer isapproximately 0.2 μm thick.

After the seed layer is deposited, another photoresist layer isdeposited onto the seed layer to be patterned prior to the metal platingprocess. Again, a photomask is positioned to mask portions of thephotoresist during an exposure to high intensity light. After theexposure, portions of the resist are removed. This process creates apatterned photoresist that has a number of recesses corresponding toeach of the etched holes in the basecoat. Each of the recesses in thepatterned photoresist is vertically aligned with one of the etched holesin the first layer of basecoat. However, the width of each of therecesses in the photoresist may greater than the width of thecorresponding etched hole to allow for metal to be plated beyond thewidth of each of the etched holes in the basecoat.

An electrically conductive metal, such as NiFe or Cu, is then platedinto each of the etched holes in the basecoat and expanded beyond thewidth of the etched hole to prevent voids from forming between the firstlayer of basecoat and each of the metal connections. This processcreates a number of electrical recessed vias, where each electricalrecessed via includes a base portion nested within one of the etchedholes in the basecoat and an upper casing. In one implementation, theupper casing is a hollow cylindrical shell. In another implementation,the upper casing has a diameter or width that is greater than a diameteror width of the underlying base portion. In yet another implementation,the upper casing has a longitudinal height that is substantially equalto the height of the first layer of the basecoat. After the buildingoperation 1210, the patterned photoresist is removed.

Another feature building operation 1215 constructs ancillary features onthe first basecoat layer to be embedded in the transducer head. Duringthe building operation, another patterned photoresist may be used toprotect portions of the transducer head. After the additional featuresare added, this layer of photoresist may be removed.

In one implementation, the feature building operation 1215 forms one ormore heaters on the first basecoat layer. In operation, such heaters canbe turned on to adjust a fly height of the transducer head above arotating media disk by thermally expanding the basecoat. In the same oran alternate implementation, the feature building operation 1215 mayattach one or more electrostatic discharge (ESD) devices to thebasecoat, such as a bleed resistor.

Another building operation 1220 plates a second metal layer inside ofthe upper casing of each electrical via and above the base portion suchthat a metal prong is added on top of the base portion and interior tothe upper casing. In one implementation, the metal prong is sized suchthat it does not contact an inner sidewall of the upper casing. Themetal prong and upper casing may also be collectively referred to hereinas the “upper portion.” During the building operation 1220, portions ofthe transducer head may again be protected by patterned photoresist.

The metal utilized for building operation 1220 is electricallyconductive and may be the same material as utilized in the metal platedby building operation 1210. However, in at least one implementation, themetal plated by building operation 1220 is a different material thanthat applied in building operation 1210.

In one implementation, the height of the metal prong above the baseportion in each of the electrical vias is less than or equal to theheight of the first layer of the basecoat. In the same or a differentimplementation, the height of the metal prong in each of the electricalvias is less than or equal to a height of the upper casing.

A basecoat application step 1225 applies a second layer of basecoat tothe transducer head, filling the potential void between the shoulders ofthe first metal layer and the base of the second metal layer with thebasecoat material.

A planarization step 1230 planarizes the surface of the transducer head,removing portions of the electrical vias and/or of the second layer ofbasecoat. Additionally, the planarization step 1230 exposes an upperedge of the upper portion on the surface of the wafer such that theupper casing and the interior prong may contact one or more contact padson an above structure, such as a bottom shield. The planarization step1230 may be performed by a lapping, polishing, milling orelectric-chemical planarization (eCMP) operation.

In one implementation, significant surface topography is removed fromthe transducer head during the planarization step 1230. In the same oran alternate implementation, substantially less than two microns oftopography remain on the transducer head after the planarization step1230. In yet another implementation, a few nanometers of topographyremain on the transducer head after the planarization step 1230. In anyor all of these implementations, the transducer head may be suitable forNIL patterning without polishing. The first basecoat layer may have aheight that is 40-80% of the combined height of the first and secondlayers of basecoat after the planarization step 1230.

In another example implementation, the height of the first basecoatlayer is substantially equal to three microns and the height of thesecond basecoat layer is substantially equal to two and a half micronsprior to the planarization step 1230. Therefore, two and a half micronsof topography are formed on top of the electrical vias by the basecoatapplication step 1225. In this case, the planarization step 1230 mayremove at least two and a half microns of material from the wafer toexpose the upper portion of the electrical recessed vias.

After the planarization step 1230, a contact pad attachment step 1235attaches a contact pad to the transducer head to be in contact with theupper portion of each of the electrical vias. In one implementation, thecontact pad contacts the upper perimeter of the outer casing and theinterior prong within the outer casing.

In another implementation, the contact pad is axially aligned with theupper portion and base portion. In yet another implementation, thecontact pad is axially aligned with the interior prong and a center ofthe base portion.

The specific steps discussed with respect to each of the implementationsdisclosed herein are a matter of choice and may depend on the materialsutilized and/or the topography-related requirements of a given system.The steps discussed may be performed in any order, adding and omittingas desired, unless explicitly claimed otherwise or a specific order isinherently necessitated by the claim language.

The above specification, examples, and data provide a completedescription of the structure and use of exemplary implementations of theinvention. Since many implementations of the invention can be madewithout departing from the spirit and scope of the invention, theinvention resides in the claims hereinafter appended.

What is claimed is:
 1. A layered microelectronic structure comprising: abasecoat layer on a substrate; an electrical via in the basecoat layerthat has a base portion and an upper portion, wherein the upper portionhas an outer casing and an interior prong, the upper portion has a widththat is greater than a width of the base portion, and the electrical viacontacts the substrate at an end of the base portion; and a contact padthat contacts the upper portion of the electrical via and is axiallyaligned with the base portion and the upper portion, wherein the contactpad is electrically connected to the substrate by the electrical via. 2.The layered microelectronic structure of claim 1, wherein the baseportion of the electrical via is plated into a hole etched in thebasecoat layer.
 3. The layered microelectronic structure of claim 1,wherein the outer casing is separated from the interior prong by a spacefilled with material of the basecoat layer.
 4. The layeredmicroelectronic structure of claim 1, wherein the interior prong and theouter casing are in contact with the contact pad.
 5. The layeredmicroelectronic structure of claim 1, wherein the interior prong isformed separately from the outer casing.
 6. The layered microelectronicstructure of claim 1, wherein the interior prong is axially aligned withthe contact pad and a center of the base portion.
 7. An electrical viacomprising: a base portion in contact with a substrate; and an upperportion that has an outer casing and an interior prong and is in contactwith the base portion and a contact pad, wherein the upper portion isaxially aligned with the base portion and the contact pad, the upperportion has a width that is greater than a width of the base portion,and the contact pad is electrically connected to the substrate by theelectrical via.
 8. The electrical via of claim 7, wherein the baseportion of the electrical via is plated into a hole etched in a basecoatlayer.
 9. The electrical via of claim 7, wherein the outer casing isseparated from the interior prong by a space filled with a basecoatmaterial.
 10. The electrical via of claim 7, wherein the interior prongis formed separately from the outer casing.
 11. The electrical via ofclaim 7, wherein the interior prong is in contact with the contact pad.12. The electrical via of claim 7, wherein the interior prong is axiallyaligned with the contact pad and a center of the base portion.
 13. Amethod comprising: building an electrical via in a basecoat layer thathas a base portion and an upper portion, wherein the upper portion hasan outer casing and an interior prong, the upper portion has a widththat is greater than a width of the base portion, and the electrical viacontacts the substrate at an end of the base portion; and building acontact pad in contact with the upper portion of the electrical via andaxially aligned with the upper portion and the base portion, wherein thecontact pad is electrically connected to the substrate by the electricalvia.
 14. The method of claim 13, wherein building the electrical viafurther comprises: plating the base portion into a hole etched in abasecoat.
 15. The method of claim 13, wherein building the electricalvia further comprises plating the interior prong on top of the baseportion within the outer casing.
 16. The method of claim 13, furthercomprising depositing a first basecoat layer on the substrate that issubstantially equal in height to the base portion of the electrical via;and depositing a second basecoat layer on top of the first basecoatlayer.
 17. The method of claim 16, wherein a total height of theelectrical via is substantially equal to the combined height of thefirst and second layers of basecoat.
 18. The layered microelectronicstructure of claim 1, wherein the basecoat layer includes: a firstbasecoat layer on the substrate that is substantially equal in height tothe base portion of the electrical via; and a second basecoat layer ontop of the first basecoat layer.
 19. The layered microelectronicstructure of claim 18, wherein a total height of the electrical via issubstantially equal to the combined height of the first and secondlayers of basecoat.
 20. The electrical via of claim 8, furthercomprising: a first basecoat layer on the substrate that issubstantially equal in height to the base portion of the electrical via;and a second basecoat layer on top of the first basecoat layer.